SummaryThe cell wall of pathogenic fungi such as Cryptococcus neoformans, provides a formidable barrier to secrete virulence factors that produce host cell damage. To study secretion of virulence factors to the cell periphery, sec6 RNAi mutant strains of C. neoformans were tested for virulence factor expression. The studies reported here show that SEC6 RNAi mutant strains were defective in a number of virulence factors including laccase, urease as well as soluble polysaccharide and demonstrated attenuated virulence in mice. Further analysis by transmission electron microscopy detected the production of abundant extracellular exosomes in wild-type strains containing empty plasmid, but a complete absence in the iSEC6 strain. In addition, a green fluorescent protein-laccase fusion protein demonstrated aberrant localization within cytoplasmic vesicles in iSEC6 strains. In contrast, iSEC6 strains retained normal growth at 37°C, as well as substantially normal capsule formation, phospholipase activity and total secreted protein. These results provide the first molecular evidence for the existence of fungal exosomes and associate these vesicles with the virulence of C. neoformans.

Mannan binding lectin (MBL) is an innate immune mediator belonging to the collectin family known to bind to the surfaces of many viruses, bacteria, and fungi. However, pathogenic strains of the fungus Cryptococcus neoformans are resistant to MBL binding. To dissect the mechanism of cryptococcal resistance to MBL, we compared MBL binding to an encapsulated wild-type strain, an encapsulated ccr4⌬ mutant defective in cell integrity, and an acapsular cap60⌬ strain. No MBL binding was detected on wild-type C. neoformans. In contrast, the ccr4⌬ mutant bound MBL to the cell wall, predominantly at the ends of enlarged buds, whereas the acapsular strain bound MBL only at the bud neck and bud scars. In addition, the ccr4⌬ mutant was sensitive to the cell wall-active antifungal caspofungin and other cell wall stress inducers, and its virulence was reduced in a mouse model of cryptococcosis. Interestingly, treatment of wild-type cells with caspofungin also increased MBL binding to C. neoformans. These results suggest that both the presence of capsule and wild-type cell wall architecture preclude MBL binding to C. neoformans.

The results of this study show no significant difference when evaluating current standard and low-dose CT scans using less than one-half the amount of exposure. This suggests that in complex extremity fractures, a new CT protocol may potentially be used. Our initial data show promise that we may retain satisfactory imaging to formulate a treatment plan while also reducing the collective radiation burden to the population.

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Background and objectives: Malignant primary chest wall tumors (PCWTs) comprise a rare group of thoracic tumors with unique anatomical considerations, and experience with wide surgical resection is limited to specialty referral centers and specific diagnoses. We investigated the tumor recurrence and overall survival (OS) for patients with a variety of PCWTs diagnoses at our institution. Methods: From 1991 to 2010, patients with malignant PCWT undergoing wide surgical resection for curative intent under a single surgeon were reviewed. Diagnosis and grade (if applicable) of surgical pathology, along with patient demographics, neoadjuvant chemotherapy or radiation therapy, and outcomes (complications, recurrence, and OS) at follow-up were analyzed. Results: One hundred fifteen patients were included in the study. The most common tumor diagnoses included pleomorphic sarcoma and liposarcoma. Negative margins were achieved in 70 (74%) of cases. Postoperative complications were reported in 21 (20%) cases. The 5-year survival rate was 54%, while the 10-year survival rate was 29%. The local and distant recurrence rates were 50% and 38%, respectively. OS was significantly less in patients with any recurrence (p < 0.001) but not significantly different between pathology grades (p ¼ 0.28). Conclusions: Wide resection for malignant PCWT is feasible when undertaken for a heterogenous group of diagnoses.